以壓痕法評估工程合金之拉伸性質

Abstract

工業所使用的大型構件中，因處在各種破壞機制之下而產生構件劣化、龜裂的現象，所以必須進行結構完整性分析或殘餘壽命評估，這些分析需掌握相關之材料機械性質。進行結構完整性分析，因無法由理論計算獲得，所以必須利用非破壞性或破壞性檢測，雖然破壞性檢測可取得更詳盡準確的資料，但其缺點為必須對構件進行取樣，影響構件之完整性，為了安全性的考量，使用非破壞性檢測或挖取構件上之少量樣品進行試驗，所以有必要開發小尺寸試片的技術。 本文研究針對壓痕法對數種系列材料做測試，驗證其泛用性，壓痕法計算之拉伸曲線與標準拉伸試驗之數據比較，利用適當之經驗公式校正以得到材料之拉伸性質。本實驗主要針對碳鋼、鈦合金、鋁合金和粉末冶金材料進行實驗，並對於文獻提供之材料參數和拉伸性質進行討論。 由於壓痕試驗機的設計，能達到體積小、待測物無須加工、材料無幾何形狀之限制等優點，且能達到縮短實驗時間，分析壓痕數據預估材料的拉伸性質。因為量測儀器體積小，所以使用壓痕法量測機械性質的技術是深具潛力，簡便且適合現場量測的非破壞性檢測材料機械性質方法，本文擬對此方法作深入探討。

Mechanical equipments in the Industry often endure from various depredation mechanism, resulting in cracks and fractures. Therefore, it is necessary to test the solidity of mechanical properties of structures and its residual life. In order to test the subjects, we have to know the relevant mechanical properties of material first. The data of structure solidity and residual life can’t be obtained from theoretical calculation. They are often collected by doing destructive or non-destructive examinations. Although destructive examinations can offer more detail than non-destructive ones, the drawbacks of destructive without affecting the solidity of the whole structure. Thus, these samples must be small enough to avoid damages on the structure, which makes developing small specimen technology crucial and necessary. This research includes performing Ball Indentation Test on machines from several classifications of testing materials, increasing feasibility of wide range of materials, comparing the data from Ball Indentation Test to general mechanical examinations, and obtaining the mechanical properties of the unknown materials by applying appropriate experimental formulas. This research mainly focuses on materials like carbon-steel, Ti-alloy, Al-alloy and the metal of powder metallurgy. In addition, material factor and true-stress/true plastic strain curve mentioned in literatures are discussed. Therefore, the design of the Indentation Test machine has several advantages, such as smaller size of samplings and elimination of the surface process of material. Most importantly, we can shorten/decrease the time of experiment. In conclusion, Ball Indentation Test is potential, simple, and suitable for on-site measurement of non-fractural/destructive examination.